ABSTRACT Recently, Brazilian agriculture and the mechanization process have been improved and developed, particularly in sugarcane cultivation. The developed processes should adopt suitable management practices in terms of the technical, economic, and operational logistical aspects. As a management tool, the present study aimed to measure the impact of the accumulated use of harvesters (life in h) and agricultural productivity (Mg · ha−1) on the harvesting operational capacity (HOC). Mathematical modeling was performed on data obtained from eight sugarcane production units, and equations corresponding to the HOC as a function of the harvester's life and the crop agricultural productivity were developed. The equation that best represented the phenomenon was selected. The values of the HOC depend on operational conditions and range from (17 to 44) Mg · h−1, thereby demonstrating significant operational and economic discrepancies. When the mean life of the harvester was 10,000 h and the mean productivity of the cane field was 80.0 Mg · ha−1, an HOC of 31.7 Mg · h−1 was obtained. It was found that agricultural productivity is directly proportional to the HOC, whereas the harvester's life is inversely proportional to the HOC; the parameters are not linear in both cases.

RESUMO A agricultura brasileira tem expandido e melhorado suas técnicas nas últimas décadas, assim como a mecanização da cultura de cana-de-açúcar. Em geral, o custo da mecanização dessa cultura é o mais elevado dentre o custo total de produção em relação a outras culturas. Este custo é composto de vários componentes, tais como o custo da colhedora. Este trabalho teve por objetivo desenvolver um modelo matemático que represente o custo operacional da colhedora em função de sua vida e da produtividade agrícola, parâmetros esses associados à capacidade operacional da colhedora. Foram realizadas simulações deste custo, variando a vida útil das colhedoras entre 0 e 17.900 h e a produtividade agrícola da cultura variou de 50 a 130 Mg ha-1. Os resultados apresentaram um custo operacional entre R$ 7,23 e R$ 26,43 Mg-1. Verificou-se que o custo operacional é inversamente proporcional e não linear à produtividade e também diretamente proporcional e não linear à idade da colhedora.

ABSTRACT The brazilian agriculture has expanded and improved its techniques in the last decades as well as the mechanization of sugarcane cultivation. Overall, the mechanization cost of this cultivation is the highest of the total cost of production in relation to other crops. That cost consists of several elements such as the cost of the harvester. This study aimed to develop a mathematical model that represents the operational cost of the harvester in relation to its operating life and agricultural productivity, parameters that are associated with its operational capacity. Simulations of this cost were conducted, raging the operating life of harvesters between 0 and 17,900 h, and the agricultural productivity of the cultivation from 50 to 130 Mg ha-1. The results indicated an operating cost between R$ 7.23 (BRL) and R$ 26.43 Mg-1. It was verified that the operational cost is inversely proportional and nonlinear to productivity, and also directly proportional and nonlinear in relation to the age of the harvester.

ABSTRACT Small rural farms are important for Brazilian agribusiness, but equipment suitable for distributing fertilizers on these properties is scarce. We studied a new fertilizer metering mechanism for use on the family farm. It combines a helical conic thread with a conventional fertilizer meter in a cylindrical section. The experimental plan was created using a 24 factorial design. An analysis of variance (ANOVA) was also conducted. The mechanism showed a positive result with respect to the uniformity of fertilizer flow (with a coefficient of variation of 3.1-5.8%), longitudinal distribution (with a coefficient of variation of 4%), and different types of fertilizers (in which variations between 2.7 and 3.5% were found).

RESUMO Na colheita mecanizada de cana-de-açúcar é utilizada uma colhedora autopropelida em conjunto com uma máquina agrícola denominada de transbordo, que tem a função de transportar o produto colhido. Os custos com o corte, carregamento e transporte variam entre 30 e 60% dos custos de produção da cana-de-açúcar. Dentre os custos operacionais de máquinas agrícolas, o custo de reparo e manutenção (CRM) possui relevância, sendo assim, objetivou-se neste trabalho determinar os parâmetros do modelo matemático do CRM em função da vida (horas de uso) para o transbordo, utilizando o método da American Society of Agricultural and Biological Engineers (ASABE). Estes modelos de CRM foram obtidos para dois conjuntos de transbordos de fabricantes diferentes e seus dados despendidos ao longo de até 12 anos. O modelo foi ajustado e posteriormente validado utilizando métodos de estatística descritiva. As equações ajustadas do CRM foram diferentes para cada conjunto de transbordo analisado, sendo portanto, uma ferramenta importante na gestão da mecanização nas usinas pois fornece elementos que podem subsidiar as tomadas de decisão dos gestores na aquisição e gerenciamento de equipamentos agrícolas.

ABSTRACT In the mechanical harvesting of sugarcane, a self-propelled harvester is used in conjunction with an agricultural implement named infield wagon, which has the function of storing and transporting the harvested product. Much of the cost of sugarcane production comes from this operation (30 to 60%). Among the operational costs of agricultural machinery, the cost of repair and maintenance (CRM) is relevant. Therefore, the objective of this study was to determine the parameters of the CRM mathematical model based on the life (hours of use) for the infield wagon, using the method of the American Society of Agricultural and Biological Engineers (ASABE). These CRM models were obtained for two sets of infield wagon from different manufacturers and their costs over up to 12 years. The model was adjusted and then validated using descriptive statistics methods. Fitted CRM equations were different for each analyzed set of infield wagon and, therefore, are a valuable tool in the management of mechanization in sugarcane mills as it provides elements that can support decision-making of managers in the acquisition and management of agricultural implements.